/*
** $Id: ldblib.c $
** Interface from Lua to its debug API
** See Copyright Notice in lua.h
*/

#define ldblib_c
#define LUA_LIB

#include "lprefix.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

/*
** The hook table at registry[HOOKKEY] maps threads to their current
** hook function.
*/
static const char *const HOOKKEY = "_HOOKKEY";

/*
** If L1 != L, L1 can be in any state, and therefore there are no
** guarantees about its stack space; any push in L1 must be
** checked.
*/
static void checkstack(lua_State *L, lua_State *L1, int n)
{
    if (l_unlikely(L != L1 && !lua_checkstack(L1, n)))
        luaL_error(L, "stack overflow");
}

static int db_getregistry(lua_State *L)
{
    lua_pushvalue(L, LUA_REGISTRYINDEX);
    return 1;
}

static int db_getmetatable(lua_State *L)
{
    luaL_checkany(L, 1);
    if (!lua_getmetatable(L, 1)) {
        lua_pushnil(L); /* no metatable */
    }
    return 1;
}

static int db_setmetatable(lua_State *L)
{
    int t = lua_type(L, 2);
    luaL_argexpected(L, t == LUA_TNIL || t == LUA_TTABLE, 2, "nil or table");
    lua_settop(L, 2);
    lua_setmetatable(L, 1);
    return 1; /* return 1st argument */
}

static int db_getuservalue(lua_State *L)
{
    int n = (int)luaL_optinteger(L, 2, 1);
    if (lua_type(L, 1) != LUA_TUSERDATA)
        luaL_pushfail(L);
    else if (lua_getiuservalue(L, 1, n) != LUA_TNONE) {
        lua_pushboolean(L, 1);
        return 2;
    }
    return 1;
}

static int db_setuservalue(lua_State *L)
{
    int n = (int)luaL_optinteger(L, 3, 1);
    luaL_checktype(L, 1, LUA_TUSERDATA);
    luaL_checkany(L, 2);
    lua_settop(L, 2);
    if (!lua_setiuservalue(L, 1, n))
        luaL_pushfail(L);
    return 1;
}

/*
** Auxiliary function used by several library functions: check for
** an optional thread as function's first argument and set 'arg' with
** 1 if this argument is present (so that functions can skip it to
** access their other arguments)
*/
static lua_State *getthread(lua_State *L, int *arg)
{
    if (lua_isthread(L, 1)) {
        *arg = 1;
        return lua_tothread(L, 1);
    } else {
        *arg = 0;
        return L; /* function will operate over current thread */
    }
}

/*
** Variations of 'lua_settable', used by 'db_getinfo' to put results
** from 'lua_getinfo' into result table. Key is always a string;
** value can be a string, an int, or a boolean.
*/
static void settabss(lua_State *L, const char *k, const char *v)
{
    lua_pushstring(L, v);
    lua_setfield(L, -2, k);
}

static void settabsi(lua_State *L, const char *k, int v)
{
    lua_pushinteger(L, v);
    lua_setfield(L, -2, k);
}

static void settabsb(lua_State *L, const char *k, int v)
{
    lua_pushboolean(L, v);
    lua_setfield(L, -2, k);
}

/*
** In function 'db_getinfo', the call to 'lua_getinfo' may push
** results on the stack; later it creates the result table to put
** these objects. Function 'treatstackoption' puts the result from
** 'lua_getinfo' on top of the result table so that it can call
** 'lua_setfield'.
*/
static void treatstackoption(lua_State *L, lua_State *L1, const char *fname)
{
    if (L == L1)
        lua_rotate(L, -2, 1); /* exchange object and table */
    else
        lua_xmove(L1, L, 1);    /* move object to the "main" stack */
    lua_setfield(L, -2, fname); /* put object into table */
}

/*
** Calls 'lua_getinfo' and collects all results in a new table.
** L1 needs stack space for an optional input (function) plus
** two optional outputs (function and line table) from function
** 'lua_getinfo'.
*/
static int db_getinfo(lua_State *L)
{
    lua_Debug ar;
    int arg;
    lua_State *L1 = getthread(L, &arg);
    const char *options = luaL_optstring(L, arg + 2, "flnSrtu");
    checkstack(L, L1, 3);
    luaL_argcheck(L, options[0] != '>', arg + 2, "invalid option '>'");
    if (lua_isfunction(L, arg + 1)) {                 /* info about a function? */
        options = lua_pushfstring(L, ">%s", options); /* add '>' to 'options' */
        lua_pushvalue(L, arg + 1);                    /* move function to 'L1' stack */
        lua_xmove(L, L1, 1);
    } else { /* stack level */
        if (!lua_getstack(L1, (int)luaL_checkinteger(L, arg + 1), &ar)) {
            luaL_pushfail(L); /* level out of range */
            return 1;
        }
    }
    if (!lua_getinfo(L1, options, &ar))
        return luaL_argerror(L, arg + 2, "invalid option");
    lua_newtable(L); /* table to collect results */
    if (strchr(options, 'S')) {
        lua_pushlstring(L, ar.source, ar.srclen);
        lua_setfield(L, -2, "source");
        settabss(L, "short_src", ar.short_src);
        settabsi(L, "linedefined", ar.linedefined);
        settabsi(L, "lastlinedefined", ar.lastlinedefined);
        settabss(L, "what", ar.what);
    }
    if (strchr(options, 'l'))
        settabsi(L, "currentline", ar.currentline);
    if (strchr(options, 'u')) {
        settabsi(L, "nups", ar.nups);
        settabsi(L, "nparams", ar.nparams);
        settabsb(L, "isvararg", ar.isvararg);
    }
    if (strchr(options, 'n')) {
        settabss(L, "name", ar.name);
        settabss(L, "namewhat", ar.namewhat);
    }
    if (strchr(options, 'r')) {
        settabsi(L, "ftransfer", ar.ftransfer);
        settabsi(L, "ntransfer", ar.ntransfer);
    }
    if (strchr(options, 't'))
        settabsb(L, "istailcall", ar.istailcall);
    if (strchr(options, 'L'))
        treatstackoption(L, L1, "activelines");
    if (strchr(options, 'f'))
        treatstackoption(L, L1, "func");
    return 1; /* return table */
}

static int db_getlocal(lua_State *L)
{
    int arg;
    lua_State *L1 = getthread(L, &arg);
    int nvar = (int)luaL_checkinteger(L, arg + 2);      /* local-variable index */
    if (lua_isfunction(L, arg + 1)) {                   /* function argument? */
        lua_pushvalue(L, arg + 1);                      /* push function */
        lua_pushstring(L, lua_getlocal(L, NULL, nvar)); /* push local name */
        return 1;                                       /* return only name (there is no value) */
    } else {                                            /* stack-level argument */
        lua_Debug ar;
        const char *name;
        int level = (int)luaL_checkinteger(L, arg + 1);
        if (l_unlikely(!lua_getstack(L1, level, &ar))) /* out of range? */
            return luaL_argerror(L, arg + 1, "level out of range");
        checkstack(L, L1, 1);
        name = lua_getlocal(L1, &ar, nvar);
        if (name) {
            lua_xmove(L1, L, 1);     /* move local value */
            lua_pushstring(L, name); /* push name */
            lua_rotate(L, -2, 1);    /* re-order */
            return 2;
        } else {
            luaL_pushfail(L); /* no name (nor value) */
            return 1;
        }
    }
}

static int db_setlocal(lua_State *L)
{
    int arg;
    const char *name;
    lua_State *L1 = getthread(L, &arg);
    lua_Debug ar;
    int level = (int)luaL_checkinteger(L, arg + 1);
    int nvar = (int)luaL_checkinteger(L, arg + 2);
    if (l_unlikely(!lua_getstack(L1, level, &ar))) /* out of range? */
        return luaL_argerror(L, arg + 1, "level out of range");
    luaL_checkany(L, arg + 3);
    lua_settop(L, arg + 3);
    checkstack(L, L1, 1);
    lua_xmove(L, L1, 1);
    name = lua_setlocal(L1, &ar, nvar);
    if (name == NULL)
        lua_pop(L1, 1); /* pop value (if not popped by 'lua_setlocal') */
    lua_pushstring(L, name);
    return 1;
}

/*
** get (if 'get' is true) or set an upvalue from a closure
*/
static int auxupvalue(lua_State *L, int get)
{
    const char *name;
    int n = (int)luaL_checkinteger(L, 2); /* upvalue index */
    luaL_checktype(L, 1, LUA_TFUNCTION);  /* closure */
    name = get ? lua_getupvalue(L, 1, n) : lua_setupvalue(L, 1, n);
    if (name == NULL)
        return 0;
    lua_pushstring(L, name);
    lua_insert(L, -(get + 1)); /* no-op if get is false */
    return get + 1;
}

static int db_getupvalue(lua_State *L)
{
    return auxupvalue(L, 1);
}

static int db_setupvalue(lua_State *L)
{
    luaL_checkany(L, 3);
    return auxupvalue(L, 0);
}

/*
** Check whether a given upvalue from a given closure exists and
** returns its index
*/
static void *checkupval(lua_State *L, int argf, int argnup, int *pnup)
{
    void *id;
    int nup = (int)luaL_checkinteger(L, argnup); /* upvalue index */
    luaL_checktype(L, argf, LUA_TFUNCTION);      /* closure */
    id = lua_upvalueid(L, argf, nup);
    if (pnup) {
        luaL_argcheck(L, id != NULL, argnup, "invalid upvalue index");
        *pnup = nup;
    }
    return id;
}

static int db_upvalueid(lua_State *L)
{
    void *id = checkupval(L, 1, 2, NULL);
    if (id != NULL)
        lua_pushlightuserdata(L, id);
    else
        luaL_pushfail(L);
    return 1;
}

static int db_upvaluejoin(lua_State *L)
{
    int n1, n2;
    checkupval(L, 1, 2, &n1);
    checkupval(L, 3, 4, &n2);
    luaL_argcheck(L, !lua_iscfunction(L, 1), 1, "Lua function expected");
    luaL_argcheck(L, !lua_iscfunction(L, 3), 3, "Lua function expected");
    lua_upvaluejoin(L, 1, n1, 3, n2);
    return 0;
}

/*
** Call hook function registered at hook table for the current
** thread (if there is one)
*/
static void hookf(lua_State *L, lua_Debug *ar)
{
    static const char *const hooknames[] = { "call", "return", "line", "count", "tail call" };
    lua_getfield(L, LUA_REGISTRYINDEX, HOOKKEY);
    lua_pushthread(L);
    if (lua_rawget(L, -2) == LUA_TFUNCTION) {         /* is there a hook function? */
        lua_pushstring(L, hooknames[(int)ar->event]); /* push event name */
        if (ar->currentline >= 0)
            lua_pushinteger(L, ar->currentline); /* push current line */
        else
            lua_pushnil(L);
        lua_assert(lua_getinfo(L, "lS", ar));
        lua_call(L, 2, 0); /* call hook function */
    }
}

/*
** Convert a string mask (for 'sethook') into a bit mask
*/
static int makemask(const char *smask, int count)
{
    int mask = 0;
    if (strchr(smask, 'c'))
        mask |= LUA_MASKCALL;
    if (strchr(smask, 'r'))
        mask |= LUA_MASKRET;
    if (strchr(smask, 'l'))
        mask |= LUA_MASKLINE;
    if (count > 0)
        mask |= LUA_MASKCOUNT;
    return mask;
}

/*
** Convert a bit mask (for 'gethook') into a string mask
*/
static char *unmakemask(int mask, char *smask)
{
    int i = 0;
    if (mask & LUA_MASKCALL)
        smask[i++] = 'c';
    if (mask & LUA_MASKRET)
        smask[i++] = 'r';
    if (mask & LUA_MASKLINE)
        smask[i++] = 'l';
    smask[i] = '\0';
    return smask;
}

static int db_sethook(lua_State *L)
{
    int arg, mask, count;
    lua_Hook func;
    lua_State *L1 = getthread(L, &arg);
    if (lua_isnoneornil(L, arg + 1)) { /* no hook? */
        lua_settop(L, arg + 1);
        func = NULL;
        mask = 0;
        count = 0; /* turn off hooks */
    } else {
        const char *smask = luaL_checkstring(L, arg + 2);
        luaL_checktype(L, arg + 1, LUA_TFUNCTION);
        count = (int)luaL_optinteger(L, arg + 3, 0);
        func = hookf;
        mask = makemask(smask, count);
    }
    if (!luaL_getsubtable(L, LUA_REGISTRYINDEX, HOOKKEY)) {
        /* table just created; initialize it */
        lua_pushliteral(L, "k");
        lua_setfield(L, -2, "__mode"); /** hooktable.__mode = "k" */
        lua_pushvalue(L, -1);
        lua_setmetatable(L, -2); /* metatable(hooktable) = hooktable */
    }
    checkstack(L, L1, 1);
    lua_pushthread(L1);
    lua_xmove(L1, L, 1);       /* key (thread) */
    lua_pushvalue(L, arg + 1); /* value (hook function) */
    lua_rawset(L, -3);         /* hooktable[L1] = new Lua hook */
    lua_sethook(L1, func, mask, count);
    return 0;
}

static int db_gethook(lua_State *L)
{
    int arg;
    lua_State *L1 = getthread(L, &arg);
    char buff[5];
    int mask = lua_gethookmask(L1);
    lua_Hook hook = lua_gethook(L1);
    if (hook == NULL) { /* no hook? */
        luaL_pushfail(L);
        return 1;
    } else if (hook != hookf) /* external hook? */
        lua_pushliteral(L, "external hook");
    else { /* hook table must exist */
        lua_getfield(L, LUA_REGISTRYINDEX, HOOKKEY);
        checkstack(L, L1, 1);
        lua_pushthread(L1);
        lua_xmove(L1, L, 1);
        lua_rawget(L, -2); /* 1st result = hooktable[L1] */
        lua_remove(L, -2); /* remove hook table */
    }
    lua_pushstring(L, unmakemask(mask, buff)); /* 2nd result = mask */
    lua_pushinteger(L, lua_gethookcount(L1));  /* 3rd result = count */
    return 3;
}

static int db_debug(lua_State *L)
{
    for (;;) {
        char buffer[250];
        lua_writestringerror("%s", "lua_debug> ");
        if (luaport_fgets(buffer, sizeof(buffer), luaport_stdin) == NULL ||
            strcmp(buffer, "cont\n") == 0)
            return 0;
        if (luaL_loadbuffer(L, buffer, strlen(buffer), "=(debug command)") ||
            lua_pcall(L, 0, 0, 0))
            lua_writestringerror("%s\n", luaL_tolstring(L, -1, NULL));
        lua_settop(L, 0); /* remove eventual returns */
    }
}

static int db_traceback(lua_State *L)
{
    int arg;
    lua_State *L1 = getthread(L, &arg);
    const char *msg = lua_tostring(L, arg + 1);
    if (msg == NULL && !lua_isnoneornil(L, arg + 1)) /* non-string 'msg'? */
        lua_pushvalue(L, arg + 1);                   /* return it untouched */
    else {
        int level = (int)luaL_optinteger(L, arg + 2, (L == L1) ? 1 : 0);
        luaL_traceback(L, L1, msg, level);
    }
    return 1;
}

static int db_setcstacklimit(lua_State *L)
{
    int limit = (int)luaL_checkinteger(L, 1);
    int res = lua_setcstacklimit(L, limit);
    lua_pushinteger(L, res);
    return 1;
}

static const luaL_Reg dblib[] = {
    { "debug", db_debug },
    { "getuservalue", db_getuservalue },
    { "gethook", db_gethook },
    { "getinfo", db_getinfo },
    { "getlocal", db_getlocal },
    { "getregistry", db_getregistry },
    { "getmetatable", db_getmetatable },
    { "getupvalue", db_getupvalue },
    { "upvaluejoin", db_upvaluejoin },
    { "upvalueid", db_upvalueid },
    { "setuservalue", db_setuservalue },
    { "sethook", db_sethook },
    { "setlocal", db_setlocal },
    { "setmetatable", db_setmetatable },
    { "setupvalue", db_setupvalue },
    { "traceback", db_traceback },
    { "setcstacklimit", db_setcstacklimit },
    { NULL, NULL }
};

LUAMOD_API int luaopen_debug(lua_State *L)
{
    luaL_newlib(L, dblib);
    return 1;
}
